Restricting period for resource using range

[contrerasandres]

I'm using the range method to restrict a resource

R = S.Resource('R',periods=range(0,21,3)

I was expecting this resource to only be available in periods 0, 3, 6, 9, 12, 15, 18.

`from pyschedule import Scenario, solvers, plotters, alt

S = Scenario('nozzle',horizon=20)

two resources

R1 = S.Resource('R1',periods=range(0,21,3))
R2 = S.Resource('R2',periods=range(1,21,3))

T1 = S.Task('T1',length=1,delay_cost=1)
T2 = S.Task('T2',length=2,delay_cost=1)

T1 += R1 | R2
T2 += R1 | R2

solvers.mip.solve(S,msg=1)
print(S.solution())`

Result: [(T2, R1, 0, 2), (T1, R2, 1, 2)]

I was expecting '[(T2, R1, 0, 3), (T1, R2, 1, 1)]'

Am I using the range function incorrectly?